Development of a rheological model for polymeric fluids based on FENE model

Rheological models for polymer solutions and melts based on the finitely extensible non-linear elastic (FENE) dumbbell theory are reviewed in this study. The FENE-P model that is a well-known Peterlin approximation of the FENE model, indicates noticeable deviation from original FENE predictions and also experimental results, especially in the transient flow. In addition, both FENE and FENE-P models have some shortcomings from the point of view of theory. To overcome these shortcomings, a new approximation of the FENE spring force has been established. It has been used to develop a modified constitutive rheological model for polymeric fluids. In the procedure of modeling, the effect of non-affine deformation is introduced into the new model. Comparison between the model predictions and experimental data presented in the literature for transient and steady shear flow of polystyrene indicates that this modified model can predict the rheological behavior of polymeric fluids with a great accuracy. The newly developed modified model could predict different slopes that can cover the behavior of most of the polymeric fluids

A novel and cost-effective double-capsule nanocomposite coating based on carbon hollow spheres with self-healing performance for corrosion protection

The ability of a cost-effective self-healing nanocomposite system to restore its protection functionality in case of a coating defect is of pivotal importance to ensure durable performance under demanding corrosive conditions. In this research, a self-healing epoxy coating was fabricated by incorporation of carbon hollow spheres (CHSs) doped separately with epoxy and polyamine as film forming agents. Graphene-based CHSs were synthesized via silica templating method in presence of sucrose as a carbon precursor. After encapsulation of epoxy and polyamine agents in CHSs denoted as Ep-DCSs and Am-DCSs, respectively, 10 wt. % and 5 wt. % of Ep-DCSs and Am-DCSs were introduced in an epoxy matrix. The final nanocomposite coating was applied on the surface of mild steel substrates. A blank epoxy coating was also used as a control sample. The synthesized CHSs were characterized before and after the silica core removal using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The CHSs loaded with the film forming agents were evaluated using thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. Furthermore, the protective and self-healing properties of the coatings were studied using electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET) and salt spray testing. The obtained results showed that the fabricated nanocomposite epoxy coating can heal appropriately the scratches applied on the surface of the coating barricading the accessibility of corrosive species to the metal substrate (Figure 1). Please click Additional Files below to see the full abstract

Thermal degradation kinetics and modeling study of ultra high molecular weight polyethylene (Uhmwp)/graphene nanocomposite

10.3390/molecules26061597Molecules266159